A husband or wife may constitute the other his or her attorney in fact, to control and dispose of his or her property for their mutual benefit, and may revoke the same to the same extent and manner as other persons. [§3401.] The fact of the marital relation does not, of itself, establish the presumption that the husband is the agent of the wife, for the transaction of business for her, but in order to bind her, he must be expressly authorized to act as agent, or she must, after knowledge of the act, expressly or impliedly ratify it. Such agency or ratification may be established by circumstances, and the degree of evidence required in such cases, is less than is necessary to establish an agency between independent parties, or the ratification by the husband, of acts done by the wife or his agent. [Sidenote: Wages of wife.] A wife may receive the wages of her personal labor and maintain an action therefor in her own name, and hold the same in her own right; she may prosecute and defend all actions at law or in equity for the preservation and protection of her rights and property as if unmarried. [§3402.] The husband is entitled to the wife's labor and assistance in the duties and obligations growing out of the marriage relation, and to her earnings, if she is not engaged in a separate business on her own account; but her earnings for services performed for others than her husband or acquired in carrying on an independent business, belong to her alone. Such earnings may be invested in property and it will be exempt from seizure for debts of her husband. She may bring actions for injuries to herself, whether of person, property or reputation in the same manner as if she were unmarried. If she suffers personal injury by which the husband is deprived of her services or society he has a right of recovery for such loss and for expenses for medicine and medical treatment. The wife cannot recover in such case, unless it appears that she has expended her own money in payment of such expenses. If, at the time of the injury she is engaged in a separate business, and death results, the husband may still recover for loss of society and expenses, but an action for damages can be brought only by the administrator of her estate. Although husband or wife may maintain an action against the other for the recovery of property, neither has a right of action for damages sustained by the infliction of personal injury, and this is true even though the one inflicting the injury has been criminally convicted and fined for the assault. [Sidenote: Property of one not liable for debts of the other.]